1. Domain Of the Invention
The invention relates to a device for treatment of a flow of liquid metal, particularly aluminium, an aluminium alloy, magnesium or a magnesium alloy.
2. State of the Art
Methods of treatment of a liquid metal flow or batch before it is cast in the form of a metallurgical product, such a shaped part, a billet or a plate, are known. Treatment of liquid metal is usually intended to eliminate dissolved gases (particularly hydrogen), dissolved impurities (particularly alkaline metals) and solid or liquid inclusions that could reduce the quality of cast products. This treatment typically includes a treatment operation by insufflation of a gas into the liquid metal, this operation being performed in a first ladle. The treatment gas may be inert and insoluble in the liquid metal (such as argon) or reactive (such as chlorine), or a mix of inert and insoluble gas. The inert and insoluble gas absorbs dissolved gas by the dilution effect and carries it with it. The reactive gas reacts with some dissolved impurities and thus generates liquid or solid inclusions which, like those already present in the liquid metal, can be eliminated by a filtration operation in a second ladle provided with a filter, such a deep bed filter.
Known treatment systems for liquid metals always have several disadvantages. In particular, known systems are voluminous installations, for which maintenance is usually complicated. Such systems require a high initial investment and introduce large operating costs.
U.S. Pat. No. 5,846,479 describes a system for inline treatment comprising a closed treatment compartment and a series of treatment gas injection nozzles arranged in line along the sides of the compartment. This system is incapable of eliminating solid inclusions.
The inventors have searched for a compact device for the treatment of liquid metals that provides an industrial and economic solution to disadvantages of devices according to prior art.